This tape is 3/4 inch wide.
We had four tape decks.
The 1965 operating system stored all user programs on magnetic tape.
The users would hand in (on paper tape) amendments to their programs in the form of edit commands, not complete programs.
The amendments would be sorted by hand into the same order as the programs on the magnetic tape,
and an updated tape of the amended programs would be generated. Each amended program would then be compiled and run.
If the amendment tapes were in the wrong order, the run failed.